The goals of this project are to detect and accurately describe peri- menopausal mood disorders, explore their pathophysiology and response to pharmacological and environmental manipulation, and to document the relationship between reproductive endocrine change and disorders of mood as a way of further investigating the neurobiology of psychiatric illness. Findings to date include: 1) significant improvement of multiple symptoms of perimenopausal depression following estrogen replacement in 31 women with perimenopausal depression; 2) decreased libido, sexual arousal, and erectile function in 20 men during Lupron- induced hypogonadism; 3) decreased vigor and exercise-associated pleasure in men during the hypogonadal state; 4) significant enhancement of visual-spatial test performance during the hypogonadal state in 20 men participating in the Lupron trial; 5) significantly elevated plasma m-CPP levels during the hypogonadal state, and significantly elevated basal and stimulated plasma prolactin levels during testosterone addback (after I.V. administration of m-CPP) in 11 men participating in the Lupron trial; 6) significantly decreased Wisconsin Card Sort Test-activated regional cerebral blood flow, as measured by O15 PET scans in eight males participating in the Lupron trial compared with testosterone addback.